The TARDIS, carrying the Doctor, Tegan and Turlough, is pulled towards the abandoned Helheim Genetic Research Facility, an isolated medical lab located at the edge of the galaxy, where a team of doctors worked tirelessly to find a cure for Richter's Syndrome, a contagious disease that was ravaging the galaxy. At the same time, Nyssa of Traken, 50 years older than when we last saw her, is investigating the same facility. There, the reunited TARDIS team finds skeletons of themselves, covered in cobwebs, sealed in a medlab, apparently undisturbed for 46 years...
Forms a loose trilogy, continued in The Whispering Forest and concludes in The Cradle of the Snake.
Cobwebs contains examples of the following tropes:
- Amnesiac Dissonance: At least one of the research crew shifts from researching the cure for Richter's for moral reasons to doing the job for the benefit of her company once she has her memories restored; the other member of the research team deliberately avoids getting her memories back to escape this fate, and the third man was basically insane to varying degrees whether or not he had his memories.
- And the Adventure Continues: While Nyssa is keen to get back to work curing the genetically-modified Richter's Syndrome, she takes advantage of the TARDIS' rather... idiosyncratic approach to direction to stick on with her old friends for a while.
- Call-Back:
- Turlough's pact with the Black Guardian and his attempt to take his own life is the subject of a heated discussion between the Doctor and Tegan, the latter still believing that Turlough is up to no good.
- Tegan mentions she misses Nyssa, before they land.
- The Doctor laments his lack of a Sonic Screwdriver.
- Nyssa mentions the possibility of Alternate Selves just like when she and the Doctor travelled to Stockbridge.
- Cobweb of Disuse: When The Doctor, Tegan and Turlough, and separately, Nyssa and LOKI, set foot in the Helheim facility, the first thing they notice is that the corridors are covered in what appear to be cobwebs, and they think it's this trope. In reality, they were protective sheathing created by maintenance robots.
- Creepy Monotone: EDGAR. Even before he went mad, EDGAR spoke in a very precise HAL-like monotone. However, once his program was irreparably damaged by Security Chief Bragg, his monotone became even flatter and more deranged-sounding.
- Death World: Helheim has a toxic atmosphere.
- Distressed Dude: Turlough gets Boundand Gagged in the past so that the Doctor, Nyssa and Tegan can go along with Officer Bragg to the alien ruins.
- Eaten Alive: Tegan and Turlough are threatened with being devoured by the Kraktids although the creatures are conveniently jettisoned into space before the devouring can actually happen. The assault is recorded by Bragg to use as an illusion against intruders as per Mind Rape below.
- The Eeyore: LOKI, EDGAR (pity him) and to a lesser extent Turlough all qualify.
- Fun with Acronyms: The Doctor surmises EDGAR must stand for Encephalic Data Gathering and Research.
- Giant Enemy Crab: Nyssa is beset upon by several large creatures that bear resemblance to crabs and scorpions (without stingers), but turns out it's Your Mind Makes It Real.
- Go Mad from the Isolation: Tegan and Nyssa think that this is the case with EDGAR. It's not the entire reason for his madness, but it can't have helped.
- Have We Met Yet?: There is some confusion at the start when the team meets EDGAR, who remembers them all even though they have no idea who/what he is.
- Heroic Sacrifice: Cardell.
- Death Equals Redemption:The Doctor: I think she died finally knowing what kind of person she was.
- Death Equals Redemption:
- Human Popsicle: Bragg freezes himself towards the end of the story.
- I Don't Like the Sound of That Place: Helheim, which is name of the Norse Underworld.
- Lampshade Hanging:Tegan: Great. Another bloody corridor.
- Laser-Guided Amnesia: The crew of the Helheim research station are wiped of their memories, so that they can focus on research and not waste time on frivolous things like missing their families or holding onto moral qualms that might impede their work.
- Limited Wardrobe: How the Doctor and his companions identify the bodies in the Medlab.
- Long Bus Trip: At least from Nyssa's point of view — for her, it's been 50 years since she last saw The Doctor, Tegan and Turlough. For the rest, it's been two days since they left her on Terminus. Tegan mentions to Turlough that she hasn't even had time to miss Nyssa, yet.
- Lovable Coward: LOKI. Half the time, he is worrying about impending doom (though whether he's just a fraidycat or secretly Genre Savvy is a great intellectual exercise for the listener), and even shoots The Doctor just because the Doctor happens to show up in his line of sight, startling him. Tegan, ever The Nicknamer, even compares LOKI to C-3PO, who had similar worrywart tendencies.
- Madness Mantra: "Pity poor EDGAR..."
- MegaCorp: The Company. They are implied to be a government unto themselves, who have enough clout to pull off horrific schemes like doing gain-of-function experiments on Richter's Syndrome, releasing the resulting virus into the wild and then selling a cure the researchers have concurrently created at an exorbitant markup.
- Mind Rape: The memory devices on Helheim can do this as a defense mechanism. All you have to do is create unpleasant memories, record them, and have EDGAR (pity him) replay them at a predetermined point when intruders show up.
- The Mole: One of the crew is (unwittingly) a spy.
- Nice Job Breaking It, Hero: Nyssa helps create the cure for Richter Syndrome. But by doing this, she helps create the newer, more powerful strain.
- Oh, My Gods!: Mixed with a touch of Anachronism Stew — The Helheim staffers seem to worship the Norse pagan pantheon, or at least swear by various Viking gods.
- The Password Is Always "Swordfish": Averted. Tegan tries the passcode 1234, but it fails.
- The Plague: Richter's syndrome, a disease that went from non-present to infecting over 6 billion people over several worlds in the span of 10 years.
- Red Herring: The alien ruins found by the Helheim team. While they seem to be setting up for a key part in the mystery, they end up being little more than
Paranoia Fuel for Bragg, who even fancies that random scratches in the ruins hold his and his colleague's names, therefore establishing themselves as the only life in the universe. - Religious and Mythological Theme Naming: Following on from "Terminus" Norse naming, with the robot Loki, the planet Helheim, and invocations of Norse Gods.
- Robot Buddy: LOKI, who is to Nyssa as Nyssa was to The Doctor. He is a Loveable Coward who sees his mission as to defend Nyssa by any means necessary, although "by any means necessary" ends up being panicking and going to "threat mode" at the drop of a hat. He is loyal to Nyssa, and once he gets it through his dense positronic matrix that they're Nyssa's friends, The Doctor, Tegan and Turlough as well.
- Shout-Out: To Star Wars — LOKI is called "R2D2" by Tegan, and acts a whole heck of a lot like C-3PO. Earlier on she calls him "Tick Tock".
- Silver Fox: Nyssa is, at least in human years, somewhere around 70. She doesn't look much over 50 due to the fact that Trakenites age slower than humans and, according to Tegan, looks quite good for her apparent age.
- The Slow Path: Nyssa re-meets the TARDIS crew after 50 years, for them it has been 2 days. She is a bit shocked by this, noting that they haven't even changed their clothes.
- Split Personality: Edgar has this. A literal one, as he absorbed LOKI's program, causing the dissasociative disorder. Bragg's attempts to purge EDGAR of the rogue LOKI programming only makes things worse.
- Stable Time Loop: The resolution to the plot depends on it, and even the plague Nyssa was investigating is revealed to have been caused by these events.
- That Was the Last Entry: There are no other entries after the one where the research team had found a cure for Richter's Syndrome.
- Timey-Wimey Ball: One of the best examples. Essentially, the story plays in reverse, with The Doctor, Tegan, Turlough and Nyssa initially arriving at Helheim after the events of the story had already occurred, and with an insane computer called EDGAR having recognized them. They stumble upon their own skeletons, at which point The Doctor rationally assumes that they died at some point in the past and that they are on borrowed time. He takes them back 30 years in the past to make sure that the Stable Time Loop he assumes is going on closes properly with their deaths, but the story ends up playing much differently — The Doctor and his companions survive, and the skeletons were actually EDGAR's attempt to recreate them so that they would come back and finally order him to self destruct. In the end, The Doctor DID close the loop, as he was the one who secretly summoned the slightly earlier version of him, Tegan and Turlough to be there to discover their skeletons.
- Tomato in the Mirror: The crew of the Helheim research station aren't what they think they are, but Bragg more than the others.
- Unwitting Instigator of Doom: To a point; Bragg's intention was to provide his employers with both the cure to Richter's and the advanced strain of the disease directly so that they could control its release for their benefit, but when he's forced to freeze himself while infected with the virus he's unthawed in an exposed environment and unleashes the disease on the wider galaxy.
- What Happened to the Mouse?: What about the alien ruins?
- You Can't Fight Fate: The Doctor says they can't save the lives of the crew of the Helheim research station just like he can't save Joan of Arc's or Franz Ferdinand's. Tegan isn't having it. It doesn't help that The Doctor is also saying this in the context of them having discovered what appears to be their own skeletons and is trying to steel Tegan for the necessity of dying here — something she, quite naturally, is going to fight tooth and nail to prevent from happening.
